The present invention relates a control assembly for a hinge connection, and more particularly to a closing control and opening free assembly for a hinge connection employed for a rotatable section such as a fallboard of pianos, a slant or drop front of desks, a display unit of notebook-sized computers, a stand for portable television set, and the like.
In a general household and office, there are various articles of furniture or implements which have a rotatable section in the up-down direction by means of the plural number of hinges or other turning fittings. Such simple hinge can turn freely in the up-down direction and is usually used for a rotatable section, for example, a fallboard of pianos, a slant or drop front of desks, a paper cutter, and a seat cover of toilet seats. When the rotatable section is closed suddenly, there is a danger of nipping and injuring a finger in the rotatable section. On such an occasion, the rotatable section suffers a slight or heavy damage.
Therefore, lap top, palm top or handy personal computers having a small display unit with a liquid crystal panel are required to be provided with an assembly for controlling the turn of a pivot attached to a hinge to be in control of opening and closing and keep from damaging them. The known control assembly used for opening and closing the display unit has a thick coiled spring fastened around the hinge pivot and both ends of the coiled spring are fixed to the holding member. As the pivot is tightened with strong torsion of the spring, the display unit rests at a desired opening position. With relation to the known assembly, about two times the force is required to start the opening and closing motion as compared with the turning movement of the display unit, as it is impossible to control the opening and closing motion due to constant tightening of the hinge pivot with uniform strong torsion. In case the opening and closing motion of the display unit are carried out repeatedly, a contact part of the pivot with the spring is worn out and frictional resistance in the hinge increases more and more as metal grounds enter the contact part. Consequently, the opening and closing motion of the display unit become difficult.
According to handy personal computers with a display unit, I have already proposed novel control assembly for hinge connection, in U.S. Pat. No. 5,333,356 and U.S. Pat. application Ser. No. 299,754 in the capacity of one of inventors. By the use of the assembly, the display unit can be easily and smoothly closed by hand and rested the section at a desired turning position. However, it is difficult to open a heavy fallboard of a piano or a slant or drop front of a desk easily and smoothly when it is opened.